The present invention relates to appratuses that are suitable for processing semiconductor devices. More particularly, the present invention relates to an apparatus having a semiconductor processing chamber, which is used to process workpieces, and a preparatory chamber, which is used for transferring workpieces without drawing atmospheric air into the processing chamber.
There is a type of semiconductor producing apparatus provided with a processing chamber for processing workpieces in a vacuum environment. Workpieces must be transferred in the vacuum environment. There is a need to shorten the time required for transferring workpieces in both vacuum and atmospheric environments. There is also a need to reduce space occupied by the apparatus. The transferring time is the time from when the transferring of one workpiece is started to when the transferring of the next workpiece is started.
FIG. 1 is a schematic plan view showing a prior art semiconductor producing apparatus 61. The apparatus 61 is provided with a processing chamber 62, a vacuum chamber 63, and two preparatory chambers 64, 65. The processing chamber 62 is under vacuum and is used to process wafers W in a vacuum environment. The vacuum chamber 63, which is also under a vacuum, accommodates a first robot 66 to transfer the wafers W.
Each preparatory chamber 64, 65 has a port. A carrier 67 is arranged in correspondence with the port of the preparatory chamber 64, while a carrier 68 is arranged in correspondence with the port of the preparatory chamber 65. A second robot 69 is arranged between the preparatory chambers 64, 65 and the carriers 67, 68. The second robot 69 transfers unprocessed and processed wafers W between the carriers 67, 68 and the associated preparatory chambers 64, 65 in an atmospheric environment.
The first robot 66 has two hands 66a, 66b. The hands 66a, 66b exchange unprocessed wafers W with processed wafers W. More specifically, one of the hands 66a (66b) exchanges unprocessed wafers W with processed wafers W in one of the preparatory chambers 64, 65. The other hand 66a (66b) exchanges unprocessed wafers W with processed wafers W in the processing chamber 62. Two wafers W are held by each hand 66a, 66b when the robot 66 transfers the wafers W between the preparatory chambers 64, 65 and the vacuum chamber 63 and between the vacuum chamber 63 and the processing chamber 62. Since two wafers W are held by each hand 66a, 66b, the transfer of the wafers W is more efficient in comparison to when only one wafer W is held by each hand 66a, 66b. Thus, the number of transferred wafers W per unit time is increased. Consequently, the length of time required for the producing apparatus 61 to transfer wafers W is shortened.
If the semiconductor producing apparatus 61 is used in a clean room, the wafers W exposed to atmospheric air must be transferred in clean environments. Thus, devices that are used to transfer wafers W in atmospheric air, such as the carriers 67, 68 and the preparatory chambers 64, 65, are installed at locations that are relatively cleaner than other locations. Devices that transfer wafers W in a vacuum state, such as the processing chamber 62 and the vacuum chamber 63, are installed at less clean locations.
In the prior art apparatus 61, the preparatory chambers 64, 65, which require a clean environment, are arranged next to each other. Therefore, the part of the apparatus 61 that is exposed to the atmosphere occupies a large amount of floor area, or horizontal area. The devices that transfer wafers W in the atmospheric air (located at the front section of the apparatus 61) occupy a large portion of the apparatus 61. Thus, the floor space requiring a cleaner environment is relatively large, which increases costs.
Accordingly, it is an objective of the present invention to provide an apparatus for producing semiconductor devices that occupies less floor area without decreasing throughput.